What surprises me most are the rave reviews in the absence of stereo (coming later), which I always thought was de rigueur for audiophiles. I look forward to those future reviews.
Personally speaking, I'd take great mono over sub-par stereo any day anyway.
That said, stereo can matter, but only when the recording itself was done in stereo. Proper stereoscopic recording is pretty cool to listen to with headphones.
All my opinion, of course.
Also, I doubt most audiophiles would use it as their primary listening source, but it may be the perfect solution for additional listening areas.
If you're bouncing audio off walls you may get ambience, but you're not going to get a clean stereo image.
Also, the KEF speakers are hardly world beaters. They have a good reputation as PC speakers, but that's not setting the bar very high.
Professional speaker manufacturers like Genelec use a similar adaptive tuning system, and you can buy a microphone and software add-on to flatten the response of any speaker.
https://www.sonarworks.com/reference
The limitations are well known. The correction curve is level-dependent, because room resonance is a time domain phenomenon created by physical standing waves in a 3D space that includes damping elements, and you can't truly correct it with a frequency domain solution.
You can approximate a time-domain correction with convolution and some assumptions about the room geometry and acoustics, but it's never going to be perfect.
Bottom line: I'm sure the Homepod sounds very nice, and - as usual - it's innovating with technology that's been available elsewhere for a while, and made much easier to use.
But it's not magic, and it's not going to sound hugely better than a much more expensive true stereo system.
Of course that'll do just fine for a lot of buyers.
Apparently there is.
https://en.wikipedia.org/wiki/Stereophonic_sound
"Stereophonic sound or, more commonly, stereo, is a method of sound reproduction that creates an illusion of multi-directional audible perspective. This is usually achieved by using two or more independent audio channels through a configuration of two or more loudspeakers (or stereo headphones) in such a way as to create the impression of sound heard from various directions, as in natural hearing.[1]"
I'm inferring from that there are other methods to create an illusion of multi-directional audible perspective.
I was surprised by the HomePod. It's much smaller than I had imagined, and sounds much better. I think I might get another one when the Airplay 2 update comes out.
today practically all new systems marketed to audiophiles are stereo, but my guess is that most would consider faithful reproduction of the signal to be more important than the number of channels if they had to pick.